Radio frequency identification (RFID) is an emerging technology in which transponder devices, also referred to as “tags,” can be read by a radio frequency signal. RFID has a wide variety of potential applications in which identification of objects or persons is desirable for tracking and/or controlling access. A principal advantage of RFID systems is that tags can be read without making physical or electrical contact to the tag. This is possible because the system is based on either inductive or electromagnetic coupling of a signal to the tag. This allows items to be read by illumination from an RFID reader.
Because RFID tags can be read without contact, it is possible for them to be read without knowledge of the tag holder. Current systems assume that because the reader will only power up the chip from a few inches away that the cardholder must present the card to the reader. However, other than this assumption, the system offers no specific way for the user to know when their card is powered up and read, and, in many applications the tag may be read from a greater distance thus making it difficult for a cardholder to know the card has been read. Also, it is possible for a tag to be illuminated by a first reader but not properly read by that reader.
In some applications, merchandise tracking and stocking for example, a number of RFID tags may form a group of tags that usefully relate to each other. These tags may be periodically read by one or more primary readers. It may be useful in certain instances for the RFID tag user to collect information about these readings. However, the information collected by these primary readers may not be easily combined if these primary readers are linked to distinct systems. Also, users of the RFID tags may be distinct from users of one or more of the primary readers.
For at least the foregoing reasons, there is a need for a secondary reading device and system that can detect and collect information about readings of one or more RFID tags by one or more primary readers.